thermal: intel: int340x: Rename variable in int340x_thermal_zone_add()

Rename local variables int34x_thermal_zone in int340x_thermal_zone_add()
and int340x_thermal_zone_remove() to int34x_zone which allows a number
of code lines to be shorter and easier to read and adjust some white
space for consistency.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Zhang Rui <rui.zhang@intel.com>